Lq4 combination? ?

**jking78** · 10-21-2014, 06:05 PM

I have a lq4 with 11000 miles. I'm shooting for a goal of 450 rwhp. I would great to see what combinations are out there. Right I have a stock ls6 intake stock 317 heads and stock bottom end. I

**scott5** · 10-21-2014, 08:06 PM

nice set of heads and a cam and you will be in the area you wanna be in.

**jking78** · 10-21-2014, 08:22 PM

Originally Posted by scott5

nice set of heads and a cam and you will be in the area you wanna be in.

I'm looking for a set of 243's

**98TransAmWs-6** · 10-22-2014, 04:33 AM

I have a set of reworked 243s for sale if interested.

**Firebirdjones** · 10-22-2014, 04:53 AM

A good set of ported heads and a camshaft to compliment should get you very close to your rwhp goals.

**scott5** · 10-22-2014, 05:34 AM

Originally Posted by 98TransAmWs-6

I have a set of reworked 243s for sale if interested.

These would definitely work to get you to your goal

**jking78** · 10-22-2014, 04:33 PM

I'm new to the ls what makes 243 better then 317 heads I have a buddy that works in a machine shop that can port and polish my 317 's would that help any

***SMWS6TA*** · 10-22-2014, 04:55 PM

if your going turbo the 317's are what you want where as for na builds the 243 is the best stock head. They flow more volume over all the rest. Also look for 799's, they are same as 243's just made somewhere else and do not come with sodium valves.

This above holds true compairing stock LS1 style heads. Different ball game with LS3 style heads.

With a 6.0liter block you have options. You can stay with LS1 style or go with LS3 style. Both have pros/cons.

**jking78** · 10-22-2014, 04:58 PM

Originally Posted by SMWS6TA

if your going turbo the 317's are what you want where as for na builds the 243 is the best stock head. They flow more volume over all the rest. Also look for 799's, they are same as 243's just made somewhere else and do not come with sodium valves.

This above holds true compairing stock LS1 style heads. Different ball game with LS3 style heads.

I do want do a turbo set but that won't be until 3-4 years down the line. Will the 243's or 799 's work with a ls6 intake

**Firebirdjones** · 10-22-2014, 05:06 PM

The 243 number is thrown around alot. Aside from the real 243 Z06 heads, the rest are just a casting number. The real Z06 heads had alot that were special about them, lightweight valves, different springs, etc... Any other 243 heads will have the casting and port shapes and combustion chamber shape there, with the flow potential, but lack the special valvetrain. May not matter to someone rebuilding heads however.

243's have a tight 64.45 cc combustion chamber but more importantly, the chambers were also designed with more swirl or mixture motion in mind. They produced a rated 10.5 compression ratio on the smaller LS6 engines. They would normally produce more on a 6.0 LQ9 with flat top pistons. With your LQ4 having dished pistons it will keep the compression ratio more in check if you decide to run these heads.

As it stands now your 317's share the same intake and exhaust runner volume as the 243's (210/75) but they don't have that combustion chamber. 317's have an open 71cc combustion chamber that produces 9.4:1.

Technically speaking, the 317's would work nicely ported, just as well as 243's in the flow department. But I'd mill them down to bump the compression and then select the camshaft to compliment it.

**jking78** · 10-22-2014, 05:12 PM

So what would I have the 317 mill down to so they can flow just as well as the 243's

**scott5** · 10-22-2014, 05:56 PM

With your 6.0 I personally would look into the rect heads. If your going boost I would be going the LSA route. The 317 heads can flow but like stated above the chamber size is what takes alil na away from them. I am using 317 heads on my current turbo 347 build. It really depends on how soon you wanna boost or if you don't mind spending alil extra now for alil more na power. The ls3 heads can also be had for your lq4 but require Alot more than just bolt on

**Firebirdjones** · 10-22-2014, 06:18 PM

You would have to mill a fair amount to get the combustion chamber down from 71 to 64. So much so that it could get into intake manifold mismatch.

It would be more probable to mill them to 67-68cc which would bump you up ( or very near) in the 10:1 compression range. A nice custom cam would get you close to your RWHP goals. Probably ~400 range.

This may or may not be worthwhile to you depending on your future goals as the others have mentioned.

I still feel aftermarket heads and cam would be the way to go. Either way you'll be changing the combo around if you boost it later. Less expensive in the long run and less work to leave the heads the way they are and just boost what you have right now, and get a cam to compliment that combo. You'll surpass your 450 RWHP goal with ease

**jking78** · 10-22-2014, 06:23 PM

Yea I believe rwhp goal is way out of range for the things I have already purchased and the amount of money I don't have

**jking78** · 10-22-2014, 06:25 PM

With that being said. What hp range would I be in with the ls6 intake and port and polished 317 heads

**Firebirdjones** · 10-22-2014, 06:48 PM

With money being an issue, honestly I'd leave the heads and compression alone. Then call one of many vendors that deal alot with LS engines to spec a custom cam to work with the 9.4 compression. Slap the LS6 intake on and be done with it for a while.

That combo would only be down a slight amount on power because of the lack of compression but you're only talking 3-4%. So you'd basically have a "cam only" LQ4 6 litre which shouldn't have any problem putting out 370-400 RWHP or thereabouts. Plenty for a fun street car. Used to be quite a few cam only 6.0's running around and they were strong.

Shucks I ran a bone stock 6.0 in my blazer straight out of an 04 truck, and after I tuned it that thing ran 14.30's in a 5,000 lbs. 4x4 blazer, lol.

**jking78** · 10-22-2014, 07:06 PM

That's very do able in my 81 malibu. I have a buddy that rework heads for a living he told me he'll port and polish them for $150 is it wroth doing

**jking78** · 10-22-2014, 07:46 PM

Firebirdjones what size injectors did you use? I have the stock ls6 injectors

**scott5** · 10-22-2014, 08:15 PM

Whats the purpose of the vehicle? Weight? Trans? All this will be needed to say which cam would fit the best in your situation. And with a cam only setup on yours depending on Cam a set of 30s would be fine. A cam only 6.0 setup with 317 heads can get you 420-450 depending on how wild you want it. Of course a cam that makes power in high rpm will net you higer hp but less tq and vice versa

**Firebirdjones** · 10-22-2014, 08:25 PM

Originally Posted by jking78

Firebirdjones what size injectors did you use? I have the stock ls6 injectors

They were the stock truck injectors, stock truck intake etc.... It was literally a complete bone stock LQ4 I pulled with 80,000 miles on it. I didn't touch a thing on it, even ran the stock truck exhaust manifolds.

The engine in stock form made a fair amount of torque, and by design that was it's intention with the long intake runner and small camshaft. Worked perfectly for what I wanted to do, and that was lug around a 5,000 lbs 72 4x4 blazer with 33" tires. I ran a built 4L60E behind it with a stock converter that came out of my 02 SS camaro. With a 3.73 gear it would pull that truck to 14.30's at 95-96 mph in the Phoenix heat.

I wouldn't hesitate to use another LQ engine just as they come, stick a cam in it, and run it in my wifes 00 SS camaro daily driver. It would make plenty of power to make us happy, and I'd bet it would likely run better than the current mild cammed LS1 in the car.